# vb2_dma_resv release-fence — RFC v2 series

Three-patch series that opts V4L2 m2m drivers into attaching real
producer fences to CAPTURE-side dmabufs, so implicit-sync GPU
consumers (Wayland / panfrost / panthor) wait correctly on the
producer's decode-completion rather than seeing the dma_buf core's
stub fence.

| Patch | Subject |
|---|---|
| `0004` | media: videobuf2: add opt-in dma_resv producer fence helper |
| `0005` | media: hantro: attach dma_resv release fence at device_run |
| `0006` | media: rockchip-rga: attach dma_resv release fence at device_run |

Numbered with the leading 4/5/6 because the fresnel build series carries
these alongside the 3 board-scoped `0001/0002/0003` Pinebook Pro DTS
patches; the numbers reflect apply-order in the PKGBUILD, not the
upstream lore series ordering (which starts at 1/4..4/4 with a cover).

## Status

**RFC v2.** Iterated on `lore.kernel.org/linux-media` after v1 was
rejected over the dma_fence finite-time contract gap and bus-locked
allocation issues. v2 attaches the fence at `device_run` instead of
QBUF, which puts allocation in slept-OK context (PM and clocks up,
job committed) — per Nicolas Dufresne's v1 review feedback.

Cover-letter reference: `marfrit/dmabuf-modifier-triage#3` (campaign
session that owns the upstream-targeting work; this directory ships
the build-tree-ready form for kernel-agent fleet consumption).

## Scope

`subsystem/media/videobuf2/` for the helper (0004), with two
driver opt-ins (0005/0006) shipped together because hantro and
rockchip-rga both need the helper to be useful on the RK35xx fleet.
Splitting 0005/0006 into `driver/hantro/` and `driver/rockchip-rga/`
was considered but rejected: they're a single contract series, and
their apply-order matters (0004 must precede). Series-as-unit beats
per-driver promote eligibility here.

## Fleet eligibility

- **fresnel** (RK3399 + hantro + Mali-G52): eligible. Carried in
  `fleet/fresnel.yaml` since 2026-05-15 (decision flipped from "defer
  to v2" to "include — v2 in this tree").
- **ohm** (RK3566 + hantro + Mali-G52): eligible. Was the original
  reproducer for the green-frames symptom. Will be carried in
  `fleet/ohm.yaml` once that manifest lands.
- **ampere** (RK3588 + hantro for some codecs): eligibility deferred —
  RK3588 uses rkvdec2 for primary decode, hantro role is narrower.
  Re-assess when `fleet/ampere.yaml` lands per issue #6.
- **boltzmann** (RK3588): same as ampere — defer.

## Upstream targeting

Not yet posted to linux-media in v2 form. Per `feedback_no_upstream.md`
the default is "build-tree only, wait for explicit ask". When/if the
upstream submission happens, this directory's `0004/0005/0006` are the
canonical source — they include the v2 commit headers (`PATCH RFC v2`,
`In-Reply-To` chain to the v1 cover-letter Message-Id).